Thermal Behavior of Arrayed‐Waveguide Grating Made of Silica/Polymer Hybrid Waveguide

The thermal behavior of an arrayed‐waveguide grating made of a silica/polymer hybrid waveguide was examined. We experimentally confirmed that the hybrid waveguide is effective to decrease the temperature and polarization dependence of the center wavelength owing to the negative thermo‐optic coefficient of the refractive index and extremely low baking temperature of the polymer cladding. However, the detachment of the polymer cladding from the silica core, which took place either during a repeated heat cycle test or during long‐term storage in atmosphere, was a serious problem for practical use.